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With UK seeing being of the order of 3 arc secs its traditional to have pixels half that ie 1.5 arc sec across. The main worry I would have would be the vignetting, but if the flats are good and the guiding good then I don’t see it as a serious problem. I use a Celestron RASA and like the images that provides. Used with a Trius 694 it gives good clean results.
The only thing I have heard against hyperstars is the fun and games of collimating them, but for photometry rather that pretty pictures thats not a huge issue.
Do let us see some results…
I’m curious, why do you think it would be any worse than anything else? Theres possibly significant vignetting at the field edge and you ideally want a sensor where the pixels arent grossly undersampled, but otherwise its business as usual. 🙂
Any chance you could post examples from those corners please?
Perhaps the lens I borrowed previously was an outlier i.e. unusually good? In that the distortion was about 25% of the extent I found with my lens.
Could you post some excerpts from the corners please so we can compare?
Also, is it symmetric? Are all 4 corners similarly distorted?
Go to some observing meetings from your local society – they are not experts, they are ordinary people like you and me and are normally more than willing to show you what they do when they set up. It can’t be difficult or we wouldnt all be doing it.
Alternatively, if you have the means, a Meade LS scope does the trick. Place on level(ish) ground with a decent view of the sky, plug it in, make coffee, come back, start observing. It fails about 1 in 10 times.
No wizardry required. I borrowed one for 6 months and had a great time.
But long term, its better to learn than spend money up front.
I’m curious. I know that like the Hawaiians the Australians relied on oral history rather than written records, but I have no idea where they stood with regard number systems and calendars? Presumably they spotted variation but didnt record the period? Have I got that right?
Yes, saw there was a lot of lightning over that way. Its all around Norwich now.
Still no breaks here. Think I’m out of luck again.
I must admit, the exo-biology argument didnt work for me either.
Isnt detecting or monitoring an exo-planet pretty much the same as an eclipsing binary – albeit an extreme case?
Would have thought it could live quite happily as a subsection of the VSS until it proves its longevity. Theres no reason progamme stars couldnt be chosen by the members or head of the subsection surely?
No one likes writing up meeting minutes quickly 🙂
Actually, I have been thinking (try not to be shocked). The use of high precision photometry required for exo-planets, the high precision astrometry required for comets and the detailed spectroscopy of supernovae moves amateurs into situations where they are very much working at a level previously associated with professionals. So perhaps, whether or not the exo-planet section appears, the BAA needs to upgrade its pro-amateur collaboration efforts and perhaps focus a bit more effort on that to ensure those with the skills and inclination will be in demand and actively engaged.
Thanks for the info. Had assumed you had tried filtered and unfiltered driven pics to measure the actual extinction – as manufacturers have been known to hype things and accidentally forget to mention important caveats. Yeah, 37% is pretty painful though. Still worth thinking about though.
Thats a really neat idea and I can see applications in other fields. How opaque do they become when energised? What sort of attenuation level could we hope for?
I programmed a mechanical shutter to go off multiple time during a single Starlight H18 CCD exposure but, due to the time taken for the shutter to operate, its its not really plausible to work much above 5Hz and even then you are knackering the shutter mechanism, if you run it for long.
Thanks for the report.
I think I heard Jodrell just got a large Lottery payment to invest in inspiring the next generation of scientists. Its good to see his legacy still playing a role in the country.
Just a quick update. As you may recall, I found that using a USB on my Dell E4310 meant the speed of the other USB socket was impacted. In fact, when a GPS dongle was being used to set system time, it meant the error could jump from 2-3 ms to 20ms.
To try to overcome this, it was suggested I try an Expresscard based USB port. I bought a Startech dual USB2 port card, but had to return it as it wasnt recognised on Win7 – even after 30 minutes with one of their helpful online advisors. So I tried instead a CSL dual USB3 socket Expresscard for £10. After loading the drivers that was immediately recognised. It works fine with all the USB kit I tried. So I connected the GPS dongle up to that, hung a Paramount MEII tracking a satellite (22Hz tracking speed updates) on one of the laptop USBs and a Starlight 694 taking very short exposures on the other. Result can be seen above. For long periods the error was 2-3ms with occasional wandering to 4ms. Really not bad at all – plugging into the main bus made a big difference. Well worth the small installation effort.
So, if timing is crucial to you, get a standalone network enabled time source and set up your own NTP server. But if 2-3ms accuracy is good enough, £20 for a GPS dongle and a CSL card will do the business.
Thats interesting. As my previous problem had been using a USB sound sampler on a shared port, I thought I should check again.
So, I was out last night using a USB GPS dongle and NMEATIME2 to set my system clock to <0.005s accuracy, controlling a telescope from TheSkyX (which uses a USB to Serial converter to talk to a Paramount) and a Starlight camera via a USB socket.
The laptop I used was a Dell E4310 (Intel i5 at 2.4GHz with 4GB memory) which only has 2 USB sockets.
I noticed that when anything was sharing a socket with the dongle, the NMEATIME2 correction timings became erratic – it assumes GPS fixes from the receiver are evenly spaced I think. So, when I connected the telescope or when sharing with the CCD my timing precision was potentially off as the attached image demonstrates (the sharp change in the trace is when I connected the telescope). Not surprising I suppose, but the timesharing aspect clearly does have some an effect on other bus users. I imagine the impact will depend upon the nature of whats sharing the port and what laptop manufacturer/model you choose.
I will try again tonight if (wonder of wonders) we get two clear nights in a row using a Dell D630 which has 4 USB ports and post the results here. Alas, I only have Dell laptops and so cannot say how this pans out with other machines.
